From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2871DC71155 for ; Tue, 17 Jun 2025 05:34:57 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id BEEEA6B0096; Tue, 17 Jun 2025 01:34:56 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id BCCA96B0098; Tue, 17 Jun 2025 01:34:56 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id ADC4E6B0099; Tue, 17 Jun 2025 01:34:56 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0016.hostedemail.com [216.40.44.16]) by kanga.kvack.org (Postfix) with ESMTP id 9D3976B0096 for ; Tue, 17 Jun 2025 01:34:56 -0400 (EDT) Received: from smtpin27.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay10.hostedemail.com (Postfix) with ESMTP id 40DD1C1A0D for ; Tue, 17 Jun 2025 05:34:56 +0000 (UTC) X-FDA: 83563778592.27.25C40CB Received: from out-186.mta1.migadu.com (out-186.mta1.migadu.com [95.215.58.186]) by imf24.hostedemail.com (Postfix) with ESMTP id 7636E180003 for ; Tue, 17 Jun 2025 05:34:54 +0000 (UTC) Authentication-Results: imf24.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=F9CaC5Ry; spf=pass (imf24.hostedemail.com: domain of hao.ge@linux.dev designates 95.215.58.186 as permitted sender) smtp.mailfrom=hao.ge@linux.dev; dmarc=pass (policy=none) header.from=linux.dev ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1750138494; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=jJt/3ijg40UkdgbEHu+hWjam/tCkpyc+k8aOeFbuq0c=; b=JT3Yqvy2PeNpgYZLTSJ1O+k0G0P8vcXWwgh3a0me1U6ISu9EOC7RdUvt1lhOoJ3airgy99 1YVaNqXvXlkxDj5Q+S8lqY9ZUHJh2inyQTBeN71ihxA09zC6VVeoTaW+indQTdGEIpC1G8 rP8KTxdhp8osz6To2LEjsztdm4LeClg= ARC-Authentication-Results: i=1; imf24.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=F9CaC5Ry; spf=pass (imf24.hostedemail.com: domain of hao.ge@linux.dev designates 95.215.58.186 as permitted sender) smtp.mailfrom=hao.ge@linux.dev; dmarc=pass (policy=none) header.from=linux.dev ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1750138494; a=rsa-sha256; cv=none; b=rGLLfNcUxvX5eV3/zrE9LzJOgGcsUSmb7/4fp3hq3g1pQt4/ZkJXkEEIZXRCNdEDFbiLGg 5bJ/h6RsCpnaPzwOp7O/PffoLC0OMD+HFTXWtWjXO6qUhO4CwHynAh4y3MGTTzbTKzKOZX kNuIu3TYuJnEOMll3NAUMAwM49M5YUg= X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1750138492; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=jJt/3ijg40UkdgbEHu+hWjam/tCkpyc+k8aOeFbuq0c=; b=F9CaC5RywkcgHZxgL6xOzQEeC2ZsS70+jV/xRcPSh8ETXX/5G+9DmlIET6OeICHdcAg4Uo HHyvGxaCSTmyj8DVLdt4MQ4YUamhC0C6uJ+FzwBoLWa7tLmtLxxsW1TiHt8zKCwDEosiAp P5IGytNTdLuEyZpugyOqhzq6Q5Urog8= From: Hao Ge To: Andrew Morton , David Hildenbrand , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Suren Baghdasaryan , Mike Rapoport , Richard Henderson , Matt Turner , Dennis Zhou , Tejun Heo , Christoph Lameter , Heiko Carstens , Vasily Gorbik , Alexander Gordeev , Christian Borntraeger , Sven Schnelle , Kent Overstreet Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-alpha@vger.kernel.org, linux-s390@vger.kernel.org, Hao Ge , Hao Ge Subject: [PATCH v4 1/1] mm/percpu: Conditionally define _shared_alloc_tag via CONFIG_ARCH_MODULE_NEEDS_WEAK_PER_CPU Date: Tue, 17 Jun 2025 13:33:57 +0800 Message-Id: In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 7636E180003 X-Stat-Signature: p9cx4jp5cwmhk5ws7jkefjfzs8tfn7u3 X-Rspam-User: X-HE-Tag: 1750138494-687417 X-HE-Meta: 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 IlSwhoDk peTnWJIi0qArNIM4wpV7uPNzRPhjZJB3HIDsJbUwYgu6pJ93kHdpSlnmTRG14gd2SxaWpkiNt35R9OgAGnS2Q97AClpXD8hZJOYjSN50jNHD9qiS2d5Vwp8KcKUsJ9O0XQopHCvQguavrsEMRPuKTMR9L1NpoX74Su4+Ks9/z37HQGgP4CdNIbyZviOzg4Nfshap1u9P7jrukBeuUwf0upjcOZyaegXsYKHtkHMKMNaa+v3/m9M0VdK086w== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: From: Hao Ge Recently discovered this entry while checking kallsyms on ARM64: ffff800083e509c0 D _shared_alloc_tag If ARCH_NEEDS_WEAK_PER_CPU is not defined(it is only defined for s390 and alpha architectures), there's no need to statically define the percpu variable _shared_alloc_tag. Therefore, we need to implement isolation for this purpose. When building the core kernel code for s390 or alpha architectures, ARCH_NEEDS_WEAK_PER_CPU remains undefined (as it is gated by #if defined(MODULE)). However, when building modules for these architectures, the macro is explicitly defined. Therefore, we remove all instances of ARCH_NEEDS_WEAK_PER_CPU from the code and introduced CONFIG_ARCH_MODULE_NEEDS_WEAK_PER_CPU to replace the relevant logic. We can now conditionally define the perpcu variable _shared_alloc_tag based on CONFIG_ARCH_MODULE_NEEDS_WEAK_PER_CPU. This allows architectures (such as s390/alpha) that require weak definitions for percpu variables in modules to include the definition, while others can omit it via compile-time exclusion. Suggested-by: Suren Baghdasaryan Signed-off-by: Hao Ge --- arch/alpha/Kconfig | 1 + arch/alpha/include/asm/percpu.h | 5 ++--- arch/s390/Kconfig | 1 + arch/s390/include/asm/percpu.h | 5 ++--- include/linux/alloc_tag.h | 6 +++--- include/linux/percpu-defs.h | 7 ++++--- lib/alloc_tag.c | 2 ++ mm/Kconfig | 7 +++++++ 8 files changed, 22 insertions(+), 12 deletions(-) diff --git a/arch/alpha/Kconfig b/arch/alpha/Kconfig index 109a4cddcd13..80367f2cf821 100644 --- a/arch/alpha/Kconfig +++ b/arch/alpha/Kconfig @@ -7,6 +7,7 @@ config ALPHA select ARCH_HAS_DMA_OPS if PCI select ARCH_MIGHT_HAVE_PC_PARPORT select ARCH_MIGHT_HAVE_PC_SERIO + select ARCH_MODULE_NEEDS_WEAK_PER_CPU if SMP select ARCH_NO_PREEMPT select ARCH_NO_SG_CHAIN select ARCH_USE_CMPXCHG_LOCKREF diff --git a/arch/alpha/include/asm/percpu.h b/arch/alpha/include/asm/percpu.h index 6923249f2d49..4383d66341dc 100644 --- a/arch/alpha/include/asm/percpu.h +++ b/arch/alpha/include/asm/percpu.h @@ -9,10 +9,9 @@ * way above 4G. * * Always use weak definitions for percpu variables in modules. + * Therefore, we have enabled CONFIG_ARCH_MODULE_NEEDS_WEAK_PER_CPU + * in the Kconfig. */ -#if defined(MODULE) && defined(CONFIG_SMP) -#define ARCH_NEEDS_WEAK_PER_CPU -#endif #include diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig index 0c16dc443e2f..b652cb952f31 100644 --- a/arch/s390/Kconfig +++ b/arch/s390/Kconfig @@ -132,6 +132,7 @@ config S390 select ARCH_INLINE_WRITE_UNLOCK_IRQ select ARCH_INLINE_WRITE_UNLOCK_IRQRESTORE select ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE + select ARCH_MODULE_NEEDS_WEAK_PER_CPU select ARCH_STACKWALK select ARCH_SUPPORTS_ATOMIC_RMW select ARCH_SUPPORTS_DEBUG_PAGEALLOC diff --git a/arch/s390/include/asm/percpu.h b/arch/s390/include/asm/percpu.h index 84f6b8357b45..96af7d964014 100644 --- a/arch/s390/include/asm/percpu.h +++ b/arch/s390/include/asm/percpu.h @@ -16,10 +16,9 @@ * For 64 bit module code, the module may be more than 4G above the * per cpu area, use weak definitions to force the compiler to * generate external references. + * Therefore, we have enabled CONFIG_ARCH_MODULE_NEEDS_WEAK_PER_CPU + * in the Kconfig. */ -#if defined(MODULE) -#define ARCH_NEEDS_WEAK_PER_CPU -#endif /* * We use a compare-and-swap loop since that uses less cpu cycles than diff --git a/include/linux/alloc_tag.h b/include/linux/alloc_tag.h index 8f7931eb7d16..4e91bf6791cf 100644 --- a/include/linux/alloc_tag.h +++ b/include/linux/alloc_tag.h @@ -88,7 +88,7 @@ static inline struct alloc_tag *ct_to_alloc_tag(struct codetag *ct) return container_of(ct, struct alloc_tag, ct); } -#ifdef ARCH_NEEDS_WEAK_PER_CPU +#ifdef CONFIG_ARCH_MODULE_NEEDS_WEAK_PER_CPU /* * When percpu variables are required to be defined as weak, static percpu * variables can't be used inside a function (see comments for DECLARE_PER_CPU_SECTION). @@ -102,7 +102,7 @@ DECLARE_PER_CPU(struct alloc_tag_counters, _shared_alloc_tag); .ct = CODE_TAG_INIT, \ .counters = &_shared_alloc_tag }; -#else /* ARCH_NEEDS_WEAK_PER_CPU */ +#else /* CONFIG_ARCH_MODULE_NEEDS_WEAK_PER_CPU */ #ifdef MODULE @@ -123,7 +123,7 @@ DECLARE_PER_CPU(struct alloc_tag_counters, _shared_alloc_tag); #endif /* MODULE */ -#endif /* ARCH_NEEDS_WEAK_PER_CPU */ +#endif /* CONFIG_ARCH_MODULE_NEEDS_WEAK_PER_CPU */ DECLARE_STATIC_KEY_MAYBE(CONFIG_MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT, mem_alloc_profiling_key); diff --git a/include/linux/percpu-defs.h b/include/linux/percpu-defs.h index 0aeb0e276a3e..5931fcad9a91 100644 --- a/include/linux/percpu-defs.h +++ b/include/linux/percpu-defs.h @@ -63,14 +63,15 @@ * 1. The symbol must be globally unique, even the static ones. * 2. Static percpu variables cannot be defined inside a function. * - * Archs which need weak percpu definitions should define - * ARCH_NEEDS_WEAK_PER_CPU in asm/percpu.h when necessary. + * Archs which need weak percpu definitions should set + * CONFIG_ARCH_MODULE_NEEDS_WEAK_PER_CPU when necessary. * * To ensure that the generic code observes the above two * restrictions, if CONFIG_DEBUG_FORCE_WEAK_PER_CPU is set weak * definition is used for all cases. */ -#if defined(ARCH_NEEDS_WEAK_PER_CPU) || defined(CONFIG_DEBUG_FORCE_WEAK_PER_CPU) +#if defined(CONFIG_ARCH_MODULE_NEEDS_WEAK_PER_CPU) && defined(MODULE) || \ + defined(CONFIG_DEBUG_FORCE_WEAK_PER_CPU) /* * __pcpu_scope_* dummy variable is used to enforce scope. It * receives the static modifier when it's used in front of diff --git a/lib/alloc_tag.c b/lib/alloc_tag.c index c7f602fa7b23..ab0936ebf38e 100644 --- a/lib/alloc_tag.c +++ b/lib/alloc_tag.c @@ -24,8 +24,10 @@ static bool mem_profiling_support; static struct codetag_type *alloc_tag_cttype; +#ifdef CONFIG_ARCH_MODULE_NEEDS_WEAK_PER_CPU DEFINE_PER_CPU(struct alloc_tag_counters, _shared_alloc_tag); EXPORT_SYMBOL(_shared_alloc_tag); +#endif DEFINE_STATIC_KEY_MAYBE(CONFIG_MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT, mem_alloc_profiling_key); diff --git a/mm/Kconfig b/mm/Kconfig index e113f713b493..00514df3eae4 100644 --- a/mm/Kconfig +++ b/mm/Kconfig @@ -929,6 +929,13 @@ config ARCH_SUPPORTS_PUD_PFNMAP def_bool y depends on ARCH_SUPPORTS_HUGE_PFNMAP && HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD +# +# Architectures that always use weak definitions for percpu +# variables in modules should set this. +# +config ARCH_MODULE_NEEDS_WEAK_PER_CPU + bool + # # UP and nommu archs use km based percpu allocator # -- 2.25.1